1. Technical Field
The present invention relates to a navigation system for vehicles that retrieves and extracts a target facility.
2. Background Art
In one of conventional navigation systems, for example, disclosed by the Japanese Patent Publication (unexamined) No.337361/1999, the system obtains date, weather information, etc. and retrieves or searches for specific facilities conforming to the obtained conditions. In this case, the search condition on date is unique, while the search condition on weather is also uniquely appointed by selecting from rain, cloudiness and fine.
However, a problem exists in that the conventional navigation systems cannot make any search taking into consideration for fuzziness. For example, it is impossible to conduct xe2x80x9csearch for an accommodation in the neighborhoodxe2x80x9d and also, in case of xe2x80x9csearch for an accommodation located within 5 kmxe2x80x9d, the search is conducted for within a definitely predetermined distance, but not conducted for any accommodation slightly over the threshold value including fuzziness.
The present invention was made to solve the above-discussed problems and has an object of providing a navigation system for vehicles by which user (e.g., driver) can make search using natural fuzzy words.
A navigation system for vehicles according to the invention comprises: a location detector section for detecting a location of a vehicle; a mapping data memory section for memorizing mapping data including various kinds of facility information; an input section; an facility search section for determining a facility to be searched according to a character string inputted from the mentioned input section and for retrieving facility information of the facility to be searched from the mentioned mapping data memory section; and a display section for displaying a location of the vehicle and the facility information outputted from the mentioned facility search section; in which the mentioned facility search section includes a fuzziness interpretation section for converting any fuzzy search word included in the inputted character string into a defined condition (quantified criterion), and retrieves the target facility using the facility information of the mentioned facility to be searched on the basis of the defined condition.
As a result, it becomes possible for user to extract any target facility by the search using natural fuzzy words.
It is preferable that the defined condition can be selectively changed.
As a result, any fussy search word is converted into one of the defined conditions required by user.
It is also preferable that the defined condition is an approximated condition, and a target facility can be extracted and outputted using the facility information of the facility to be searched on the basis of the approximately defined condition.
As a result, it becomes possible to define the fuzziness around a certain threshold value and to retrieve and extract the target facility from the fuzzy word.
It is also preferable that the fuzziness interpretation section converts a plurality of inputted fuzzy search words into a plurality of defined conditions and, at the same time, judges a conjunctive relation between the mentioned plurality of fuzzy search words.
As a result, it becomes possible to appropriately retrieve and extract the target facility from the plurality of fuzzy search words having the conjunctive relation with each other.
It is also preferable that the fuzziness interpretation section converts a plurality of inputted fuzzy search words into a plurality of approximately defined conditions and, at the same time, judges a conjunctive relation between the mentioned plurality of fuzzy search words. As a result, it becomes possible to define the fuzziness around a certain threshold value and, it becomes possible to appropriately retrieve and extract the target facility from the plurality of fuzzy search words having the conjunctive relation with each other.
It is also preferable that fuzzy search words are converted into approximately defined conditions and reliability in the mentioned fuzzy search words is acknowledged for the facility extracted on the basis of the approximately defined conditions.
As a result, it becomes possible to find a target facility with higher reliability.
It is also preferable that fuzzy search words are converted into approximately defined conditions and reliability in the mentioned fuzzy search words is acknowledged for the facility extracted on the basis of the approximately defined conditions using a membership function established for the mentioned fuzzy search words.
As a result, it becomes possible to find a target facility with higher reliability.
It is preferable that fuzzy search words of negative meaning are converted into approximately defined conditions and reliability in the mentioned fuzzy search words of negative meaning is acknowledged for the facility extracted on the basis of the approximately defined conditions, using an established membership function.
As a result, it becomes possible to find a target facility with higher reliability.